American market research firm IDC believes wearable computers took a huge step forward last year and that shipments of smartwatches and related devices will grow by 78% annually until 2018. 

It expects the number of wearables to exceed 19 million by the end of 2014, three times larger than in 2013. That number should jump to almost 112 million by 2018.

For the first time, IDC has released a wearables forecast that divides the market into three categories: complex accessories, smart accessories and smart wearables.

IDC said complex accessories include fitness bands worn on the wrist such as FuelBand, Fitbit and Nike . Some of these devices cost just $50 but mostly priced at $100. IDC expects this category to be the most popular through 2018.

Smart accessories will slowly gain momentum and surpass shipments of complex accessories by 2018, IDC said. These devices also depend on connections to IP-capable hardware like smartphones, but allow users to add third-party apps to boost features and functions.

Examples of smart accessories are the Samsung Galaxy Gear smartwatch, which works with some Galaxy smartphones; the Sony SmartWatch and Pebble smartwatch. IDC said the value proposition of this category has yet to be completely clarified 

The third and most complex category is the smart wearables such as Google Glass. It won't be until 2016 that shipments of smart wearables exceed two million units shipped. Smart wearables will be almost fully independent of other devices except for access to the Internet.

IDC said that to succeed, smart wearable vendors must convince users to shift to a new user experience while offering them a robust selection of third-party applications.

"It is not a question of if, but when wearables as a whole will extend into the enterprise," IDC believes.